Molecular-based imaging provides new opportunities to assess vital cellular processes in vivo. The ability to monitor the molecular processes of cancer via non-invasive imaging may provide critical information regarding the effects of therapy. In the context of pre-clinical research, the use of in vivo imaging permits the acquisition of a complete dynamic biodistribution study in each animal, thereby reducing the number of animals required to reach a statistically adequate result;often the techniques used in small animal imaging are directly transferable to the clinical setting. The Small Animal Imaging Core (SAIC) is a new shared resource dedicated to providing investigators access to the state-of-the-art in small animal imaging capabilities for use in basic and translational research relevant to the mission of the City of Hope Cancer Center. Specific aims of the SAIC include: (1) maintaining a thorough understanding of the current capabilities and limitations of small animal imaging as they pertain to cancer research;(2) implementing, developing, calibrating, maintaining, and operating relevant imaging systems within the context of a small animal imaging laboratory;and (3) optimizing the use of small animal imaging in research at City of Hope by consulting with investigators. Core personnel currently include a Director, an imaging physicist, and a manager, all of whom are highly experienced in the use of imaging for research with animals. Small animal imaging systems in operation include two units for bioluminescence optical imaging (I VIS 100, Xenogen Corp.);a gamma camera (Y IMAGER, Biospace, Inc.);a PET scanner (microPET R4, CTIMI, Inc.);and a CT scanner (microCAT II Hi Res, CTIMI, Inc.). The microPET and microCAT are readily used in tandem to generate co-registered functional-anatomic PET/CT images. The Animal Resources Center has provided four rooms within the Parvin Biomedical Research Building for use by the animal imaging program (one room for the microPET, microCAT, and the y-IMAGER;two rooms for the Xenogen MS machines;and one room for a gamma counter). A system has been developed for billing users for a portion of the costs of the imaging procedures. During the first 12-month reporting period, the SAIC was used by 13 Cancer Center members from 3 Research Programs and peer-reviewed usage represented 89% of total usage. Annual budget for the core is $165,922 (97% institution, 3% chargebacks);42% ($70,000) is being requested from the CCSG.